In contrast to for example "Planescape: Torment" your dialog options in the "Baldur's Gate"-series aren't depending on the intelligence, wisdom, charisma or alignment of your character. Not much, that is. Usually you even get to choose witty remarks and clever comments while playing a rather retarded barbarian who is barely able to remember his name. But there are some situations in the game when they do matter.

Let me name a few:

- When Solaufein instructs you to rescue Phaere from the "devourers", your PC's intelligence defines his capability to identify the latter as "Illithids", "Mindflayers" or - blatantly wrong - "Otyugh".

- In Spellhold you can convince Lonk the Sane to free the prisoners without having to kill or bribe him if your charisma is high enough.

- You have to be of evil alignment to offer Adalon's eggs to the demon in Ust Natha.

- I read here that poisoning the Druid Grove is another opportunity you only get when your PC is evil. Never tried, since I prefer to play neutral characters.

I'm pretty sure that there have to be a lot more situations in which alignment or stats influence your dialog options, possibilities to solve quests or the reward you get. Do you know more of these?

for most non-cleric NPCs wisdom seems to be a useless stat, but once you cast "limited wish" it becomes clear why it is vital not to be a total dumbass. And "Wish" (ToB) shows even more possibilities for a wise character.

p.s.: please excuse typos, I'm dead drunk.

don't forget a moderately-high wisdom allows you to talk the spectator beholder out of guard duty instead of killing him.

(I think it's wisdom anyway, might be int)

Some conversations check the PC's stats, some check those of the "party leader" (whoever's portrait is at the top of the right-hand column), and some check those of the person who's actually doing the talking.

Many conversations check for CHA, but the Ring of Human Influence is used so commonly that the low-CHA conversation options for many dialogues are never even seen.

Only Neutral or Evil speakers are given the option to betray Garren Windspear.

It's the CHA of the party leader that matters when buying things in stores.

The best example of stats determining conversation options in the whole game is during the Mae'Var quests, when Edwin tells you to get some documents off a fat guy named Marcus. Now, anyone can simply buy the letters off Marcus, and if you're a Rogue you can pickpocket them (with varying odds of success), but if your CHA is high enough, you can intimidate Marcus into simply giving you the goods, and if your STR is high enough, you can (break his neck quickly and quietly).

Or, if you're a female with high CHA, you can flirt Marcus into giving the documents to you.